Calibrating means for control devices



Oct. 30, 195-1 G. c. HARBISON 2,573,437v

CALIBRATING MEANS FOR CONTROL DEVICES' Filed Nov. 268, 1949 Geof-ge C. Her-bison,

bg@%-/ M% His Attorney.

Patented Oct. 30, 1951 2,573,437 CALIBRATING MEANS 'FOR CONTROL DEVICES George C. Harbison, Erie, Pa., assignor to General Electric Company, a corporation of New York Application November 26, 1949, Serial No. 129,668

1 Claim.

My invention relates to control devices and more particularly to control devices for refrigerating systems.

In refrigerating systems, some arrangement is usually provided for controlling the flow of refrigerant in order to maintain a predetermined temperature. Some variations may occur in the manufacture of such control devices, so that some arrangement for calibrating individual de- -vices is desirable. It is an object of my invention to provide an improved arrangement for calibrating such control devices.

Further objects and advantages of my invention will become apparent as the following description proceeds and the features of novelty which characterize mygi nvention will be pointed out with particularity in the claim annexed to and forming part of this specification.

For a better understanding of my invention, reference may be had to the accompanying drawing in which Fig. 1 is a sectional plan view of a refrigerator including an embodiment of my invention; Fig. 2 is a schematic illustration of a refrigerating system incorporating the control device; and Fig. 3 is an enlarged view of a portion of the refrigerator with the control device illustrated in a section taken generally along the line 3-3 in Fig. 2.

In carrying out the objects of my invention, a temperature responsive element is provided which is movable to various positions along a temperature gradient between the inner and outer walls of a refrigerator to calibrate a control device.

Referring to Fig. 1, there is shown a refrigerator cabinet I including an outer wall 2 and a spaced inner wall or liner 3. The inner wall 3 is shaped to define a food storage compartment 4. The access opening of the food storage compartment is closed by a door 5. The space between the inner and outer walls 2, 3 is filled with a suitable heat insulating material 6. Also arranged within the space between the inner and outer walls is a control device I.

A refrigeratin system for cooling the compartment 4 is shown schematically in Fig. 2. A primary refrigerating system including a primary evaporator 8 is provided for cooling a freezing compartment defined by a liner 9. The primary evaporator is secured to the exterior of the liner and is supplied with refrigerant from a suitable condensing unit (not shown). The primary evaporator includes a section III arranged along one wall of the liner 9. The food storage compartment 4 is cooled by a secondary refrigerating system H, which includes a condensing portion i2 and an evaporating portion l3 connected in closed circuit relationship and filled with a suitable vaporizable fluid. The condensing portion I2 is arranged in heat exchange relationship with the section ill of the primary evaporator. The evaporating portion l3 may be arranged in serpentine fashion along the exterior of the liner 3 of the food storage compartment 4 in a manner well known in the art, or it may be, if desired, disposed within the compartment 4.

The control device 1 is connected in communication with the condensing portion I2 and the evaporating portion i3, and controls the flow of liquid refrigerant from the condensing portion l2 to the evaporating portion l3. Liquid refrigerant is supplied from the control device I to the evaporating portion l3 through a conduit l4 and vaporized refrigerant passes from the evaporating portion to the control device through a conduit l5. vaporized refrigerant flows from the control device through a conduit I6 to the condensing portion I2, is condensed because of heat extracted by the primary evaporator section l0, and the condensed refrigerant returns to the control device through a conduit H. The arranging of the conduit l6 and I! in heat exchange relationship is not part of my invention, but is described and claimed in Patent 2,503,922, issued April 11, 1950, covering an invention of Frank A. Schumacher, and assigned to the assignee of the present application.

Referring to Fig. 3, it can be seen that the control device or valve 1 includes a housing 3 comprising two parts l9 and 20. The housing is divided into two chambers 2| and 22 by a partition or wall 23. The partition includes a movable element or bellows 24 which is employed to control the valve element 25. Both ends of the evaporating portion i3 are in open communication with the chamber :I through the conduits L4 and I5 so that a pressure corresponding to the temperature of the-evaporating portion I3 is exerted against the interior of the bellows 24. The chamber 22 is charged with an inert gas, such as nitrogen, which exerts an opposing pressure against the exterior of the bellows 24. At a predetermined maximum temperature and, hence, pressure of the evaporating portion 13, a force is exerted against the interior of the bellows 24 from the chamber 2|, which overcomes the opposing force of the gas within the chamber 22 and effects opening of the valve element 25. Conversely, at a predetermined minimum temperature and pressure of the evaporating portion It, the pressure exerted against the interior of the bellows 24 is overcome by the opposing force exerted by the gas in the chamber 22 and the valve is closed.

There may be variations in the performance of the valve or control device I because of manufacturing tolerances. and I have provided an arrangement for factory calibration of the device to compensate for such variation. In this arrangement, a temperature-responsive bulb 25 is disposed within the space between the inner and outer walls 2 and 3 and is connected in com-- munication with the chamber 22 by a deformable tube 21. The tube 21 extends in a direction generally parallel to the walls 2 and 3, as shown in the drawing. Thus, the temperature of the bulb 26 affects the pressure-of the gas within the chamber 22-and, hence, aflects the opposing force exerted against the exterior of the bellows 24. The inner liner 3 of the food storage compartment 4 may be maintained at a temperature of, for example, 35 Fahrenheit, whereas the outer wall 2 of the refrigerator is maintained at ambient temperature, which may be, for example, in the neighborhood of 75 Fahrenheit.

' Accordingly, there is a temperature gradient from the wall 2 to the wall 3 through the intervening space, the temperature becoming progressively lower the greater the distance from the outer wall and the less the distance from the inner wall. This condition is utilized in my calibrating arrangement. Thus, the bulb 26 may be moved to a plurality of positions at varying distances from the outer wall 2 and the inner wall 3; for example, the bulb may be placed in the positions indicated by the dotted lines at 2B and 28. In the position indicated at 28, the bulb has been moved closer to the outer and higher temperature wall 2 so that the temperature of the bulb is higher than in the solid line position. This increase in temperature'and the resultant increase in pressure of the gas within the bulb causes an increase in pressure within the chamber 22 and, hence, an increase in the opposing force exerted against the exterior of the bellows. Conversely, shifting of the bulb to the position indicated at 29 causes a lowering of the temperature of the bulb and, consequently, a reduction in the pressure exerted in the chamber 22. It can be seen, therefore, that the control device I can be readily calibrated by moving the bulb 26 along the temperature gradient between the inner and outer walls, so that the control device maintains the food storage compartment within the desired temperature range despite slight variations in the manufacture of various control devices.

While I have shown and described a specific embodiment of my invention, I do not desire my invention to be limited to the particular constructions shown and described, and I intend, by

the appended claim, to cover all modifications within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

In combination with a refrigerator having spaced inner and outer walls, said walls being at diflerent temperatures whereby a temperature gradient exists through the space from one wall to the other, a control device having a closed.

. chamber, a movable element in one wall of said chamber, said chamber containing a charge of gas acting on said movable element, a temperature-responsive bulb disposed in the space tween said inner and outer walls, a deformable tube for connecting said bulb in communication with said closed chamber, said tube being disposed between said inner and outer walls and extending in a direction generally parallel to said inner and outer walls, said bulb being mounted on the free end of said tube, said tube being bendable to assume various angles with respect to said inner and outer walls, whereby the distance of said bulb from said inner and outer walls is varied for calibrating said device.

GEORGE c. HARBISON.

REFERENCES CITED The following references are of record in the file of this patent:

Germany Oct. 8, 1913 

